This invention relates to a CD-ROM (compact disk read only memory) apparatus and, more particularly, to a CD-ROM apparatus used as an external memory of a personal computer.
A general connection example of a conventional CD-ROM apparatus of this type for a personal computer system will be described by referring to FIG. 2 (Prior Art). Numeral 1 denotes a body of a personal computer, and numeral 2 designates a CPU. A ROM 3 and a RAM 4 of an internal memory are connected to the CPU 2. The CPU 2 is connected to an AT-BUS 6 through a BUS controller 5, and further connected to devices through the AT-BUS 6.
On the other hand, with respect to an external memory, an IDE-BUS I/F (interface) 7 is connected to the AT-BUS 6, and hard disk devices 8 are connected to the IDE-BUS I/F 7 through an IDE-BUS 9. In this case, the hard disk devices 8 can be connected to the IDE-BUS I/F 7 according to the IDE standards. An ISA-BUS I/F 10 is connected to the AT-BUS 6. An I/F CARD connector 12 is connected to the ISA-BUS I/F 10 through an ISA-BUS 11, and a CD-ROM apparatus 13 containing an I/F 13a corresponding in operation to the ISA-BUS standard is connected to the IF/CARD connector 12 through an I/F CABLE 14.
The conventional CD-ROM apparatus of the personal computer, as described above, is connected to the ISA-BUS I/F 10 through the I/F CARD connector 12. That is, when the CD-ROM apparatus 13 is used as an external memory, the I/F CARD connector 12 and the I/F CABLE 14 are required in addition to the CD-ROM apparatus 13. When the user connects the CD-ROM apparatus 13 to the personal computer 1, it is necessary to supply and set the I/F CARD connector 12 into the computer 1.
Therefore, eliminating the I/F CABLE 14 and the I/F CARD connector 12 would make for a simpler connection of the CR-ROM apparatus 13 to the computer 1.
Accordingly, it is an object of this invention to provide a CD-ROM apparatus which can simplify and reduce expenses in construction of a personal computer system.
The present invention achieves the above-described object, by providing a CD-ROM apparatus comprising an IDE interface, wherein a hard disk unit and the CD-ROM apparatus are connected in cascade with the IDE interface (IDE I/F) of a personal computer.
The IDE I/F of the personal computer is partitioned for both master and slave devices. The hard disk unit is ordinarily connected to the master partition. Further, the CD-ROM apparatus is ordinarily connected to the slave partition of the IDE I/F of the personal computer. Thus, the CD-ROM apparatus is connected in cascade with the hard disk unit on an IDE-BUS connected to the IDE I/F. However, according to an embodiment of the present invention, the CD-ROM apparatus may be connected to the master partition and the hard disk connected to the slave partition of the IDE I/F by changing the logic state of a drive selection bit in the IDE bus interface.